Fluid amplifier



March 31, 1970 G. B. RICHARDS FLUID AMPLIFIER 3 Sheets-Sheet 1 FiledMarch 16, 1967 zWVWfOF. e 5 54/4 57/ 6'! [bag March 31, 1970 G. B.RICHARDS FLUID AMPLIFIER Filed March 16, 1967 March 31, 1970 I G. B.RICHARDS FLUID AMPLIFIER 3 Sheets-Sheet 5 Filed March 16, 196'?lllllllnulll lllll l ll n lllullllllh NIL W United States Patent O3,503,410 FLUID AMPLIFIER George B. Richards, P.O. Box 278, HighlandPark, Ill. 60035 Filed Mar. 16, 1967, Ser. No. 623,740 Int. Cl. F15c N08US. Cl. 137--81.5 19 Claims ABSTRACT OF THE DISCLOSURE A fluidic elementemploying a boundary layer self-attachment principle and/or the Coanadaboundary layer wall-attachment principle in which the power jet is annular and the control fluid exerts control pressure upon a generallyannular or cylindrical surface of the power jet to cause the power jetto flow into either a central outlet or a surrounding annular outlet.Various embodiments and variations are presented.

CROSS-REFERENCE TO RELATED APPLICATION George B. Richards applicationSer. No. 648,602 filed June 26, 1967 for Fluid Amplifier is acontinuation-inpart of the present application.

BACKGROUND OF THE INVENTION Field The invention lies in the field ofpure fluid (fluidic) devices, which employ no moving parts, in which apower jet is directed into one of two or more distinct outlets. Thefield is further refined to devices in which control is effected throughpressure of a secondary fluid rather than through the momentum-exchangeprinciple.

Prior art The following are examples of prior art of which applicant isaware: Carlson, Patent No. 3,039,490, June 19, 1962; Horton, Patent No.3,122,165, Feb. 25, 1964; Horton et al., Patent No. 3,185,166, May 25,1965; Lewis et al., Patent No. 3,276,423, Oct. 4, 1966.

Fluid Interaction Control Devices, by C. L. Mamzic, delivered at theFifth National ISA Chemical and Petroleum Instrumentation Symposium, May5, 1964;

Design GuidePure Fluid Devices, 0. Lew Wood, Machine Design, June 24,1965;

Fluidics and Fluid Power, by Russ Henke, Machine Design, Nov. 25, 1965;

Focused-Jet Inverter, by Joseph M. Kirshner (paragraph 15.5.4, 238),Fluid Amplifiers, Copyright 1966;

Fluid Element Data Sheet pp. 5-60, Fluid Amplifier State of the Art,Volume I, Research and Development- Fuid Amplifiers and Logic, preparedunder Contract No. NAS 8-5408 by General Electric Company, NASAContractor Report NASA Cr-101, Oct. 1964;

Basic Requirements for an Analytical Approach to Pure Fluid ControlSystems, by H. L. Fox and F. R. Goldschmied, Proceedings of the FluidAmplification Symposium, May 1964, p. 293.

Some of this prior art relates to momentum-exchange devices, which areproperly outside the field of the invention, but they are listed topermit a broader understanding of the improvements afforded through theinvention.

No representation is made or intended that a search has been made orthat no better art is available than that listed.

SUMMARY The fluidic device of this invention improves on those in theprior art by providing considerably faster response in switching, byproviding increased stability for the same 3,503,410 Patented Mar. 31,1970 control pressure when used as a monostable or bistable device, byproviding greatly increased frequency of switching when used as anoscillator, and by providing for greatly increased amplification. Theinvention provides the capability for controlling power jets of greaterdensity for the reason that approximately three times or more of thearea of the power jet is exposed directly to the control pressure ascompared with a planar device; this capability is further enhanced bythe fact that the power jet of this invention needs to be deflected onlyabout one-quarter or less the deflection required for a comparableplanar device, and the angle of deflection is accordingly much smaller.

The power jet in the modulated annular jet fluidic ele ment of thisinvention permits a fluid particle in the power jet to travel in astraight line as compared with the circuitous route required in afocused jet device, for example. This feature reduces the overall lossesthrough the modulated annular element. The two or more axisymmetricoutlet ports, a first circular and having its major axis common with thelongitudinal axis of the entire element, together with the one or moreadditional outlet ports represented as successive annuli surroundingsaid first circular outlet port, require the least deviation fromstraight line travel of a particle of liquid in a power stream forswitching.

The aspect ratio, or the relationship of the power stream annulusdiameter to the thickness of a section of this annulus, may be less thanunity. The aspect ratio is independent of design considerations otherthan the quality and the quantity of fluid in the power stream.

The internal and external control annuli provide adequate space for theuse of a plurality of control duct connections.

The annular power jet design eliminates the top and bottom plate effectupon the power jet flow.

The design is such that no transition takes place from square to roundducts, which results in a low noise level.

The configuration is such that the envelope dimensions are the smallestpossible for a fluid amplifier of the boundary layer self-attachmentand/or Coanda wall-attachment class.

Embodiments of the invention themselves to molding in plastics as wellas fabrication by the welding of standard metal tubing and tubingfittings with relatively low cost.

These and other advantages are achieve through employment of theboundary layer attachment effect (selfattachrnent and/orwall-attachment) in a fluidic element using an annular power jet whichis controlled by a secondary fluid exerting control pressure in anannular area to accomplish switching of the power jet between two ormore distinct outlets. The resultant high-speed switching permits moreeflicient use as a fluid control element or as a logic element for acomputer or numerical control. High-speed switching together with highpressure recovery permit use as a building block in the field of viscousfluid control, for example, and often eliminate the necessity foremployment of interface elements.

The various objects of the invention are to provide an improved fluidicdevice for achieving the various advantages heretofore and hereinafterstated or implied.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a perspective view of oneembodiment of a fluidic device according to the present invention, withparts broken away and in section to illustrate the annular form of thepower jet, showing the power jet converging and directed to a centraloutlet;

FIGURE 2 is a schematic longitudinal sectional view of the fluidicdevice of FIGURE 1;

FIGURE 3 is a schematic longitudinal sectional view of a secondembodiment of fluidic device according to this invention, arranged as amonostable element;

FIGURE 4 is a schematic longitudinal sectional view of a thirdembodiment of fluidic device according to the present invention,arranged as a bistable element;

FIGURE 5 is a sectional view taken along line 55 of FIGURE 4,illustrating the annular form of the power jet at the point of dischargeinto the interaction area;

FIGURE 6 is a sectional view taken at the point of discharge of arectangular power jet into the interaction area of a conventional planarfluidic device, showing a power jet of approximately the same volume asthat of FIGURE 5 and illustrating the greatly reduced control pressurearea as compared with the annular power jet of FIGURE 5; and

FIGURE 7 is a schematic longitudinal sectional view of a fourthembodiment of fluidic device according to the present invention,arranged as an oscillator.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The fluidic device of FIGURES land 2 is generally designated by the reference numeral 10. It comprisesa generally tubular outer housing or casing 12 having a tubular inletportion 14 at one end, and a tubular outlet portion 16 at the other end.The inlet and outlet portions may be arranged at 90 to the centralportion as shown, but this is not required, since the inlet and outletmay be arranged in any aligned or angular relationship to one another.The inlet portion 14 has a power jet inlet 18, and the outlet portion 16has a power jet outlet 20.

A control tube 22 has its inner end portion 24 fixedly secured inradially spaced relation within an inlet section 26 of the tubularcasing 12. The outer end portion 28 of the control tube 22 extends outof the tubular casing 12, and the casing is sealed about its juncturewith the outer surface of the control tube. An annular passage 30 isformed between the control tube portion 24 and the opposed inner wallsof the tubular casing 12 to form an annular power jet. An annular powerjet nozzle 32 is formed at the downstream end of the control tube 24. Itwill be seen that the portion of the fluidic device upstream of thepower jet nozzle 32 comprises the inlet section 26.

An outlet tube 34 has its inner portion 36 fixedly secured within thetubular casing 12 with its upstream end spaced substantially downstreamof the power jet nozzle 32. The outer end portion 38 of the outlet tubemember 34 extends beyond the tubular casing 12 as shown. The tubularcasing 12 is sealed about its juncture with the outer surface of theoutlet tube 34. An annular power jet passage 40 is provided between theouter portion 36 of the outlet tube 34 and the adjacent inner walls ofthe tubular casing 12. An internal tubular passage 42 through the outlettube member 34 provides another outlet passage, With an inner outletport 44 and an outer outlet port 46. The longitudinal portion of thetubular casing 12 between the power jet nozzle 32 and the inner port 44of the outlet passage 42 comprises an interaction section 48 of thefluidic device 10. The end portion of the tubular casing 12 downstreamof the outlet port 44 comprises an outlet section 50 of the fluidicdevice.

In this particular embodiment of the invention the annular power jetinlet passage 30 and the annular outlet passage 40 have the same radiusfor their annular centerlines and the radial thickness of the inletpassage 30- is less than the radial thickness of the outlet passage 40.The power jet may be any fluid, but for purposes of illustration it isconsidered to be a liquid such as water. The momentum of the power jetcauses it to flow out of the outlet passage 40, unless the power jet issubjected to external influences. Thus the annular outlet 40 is referredto as the preferred outlet, and the tubular passage 42 is referred to asthe secondary outlet.

The internal passage through the control tube 22 provides a controlpassage 52, having a control port 54 at its inner end and a control port56 at its outer end. The control port 56 and the control passage 52 areadapted for being selectively closed by means of a suitable valve, suchas the valve disc 58, shown in the open position in FIGURE 2 and in theclosed position in FIG- URE 1.

An annular step 60 is provided at the juncture of the inlet section 26with the interaction section 48 of the tubular casing 12, with theinteraction section being larger in diameter. The power jet nozzle 32 isradially aligned with the step 60, as shown. A second control port 62 isformed through the wall of the interaction section 48 immediatelydownstream of the power jet nozzle 32 and the step 60. A suitable valveis provided for selectively opening or closing the control port 62, suchas the valve disc 64, shown in the closed position in FIGURE 2 and inthe open position in FIGURE 1.

The annular step 60 is of suflicient depth to accommodate formation ofan annular separation bubble 66 where the power jet flow is spaced fromthe wall as it is ejected from the power jet nozzle 32 into theinteraction section 48 when the control port 62 is closed and thecontrol port 56 open, as illustrated in FIGURE 2. The separation bubble66 is a low pressure area caused by entrainment of the air by the outersurface of the power jet stream, which air cannot be replenished withthe control port 62 closed. The internal surface of the power jet in theinteraction section also entrains air, but this air is replenished,inasmuch as the control port 56 is open, thus providing pressure of asecondary fluid, air. Hence, the pressure against the internal surfaceof the power jet is greater, and the pressure differential causes thepower jet to diverge and to attach to the inner wall of the interactionsection 48 downstream of the annular separation bubble 66. Thisseparation bubble formation and downstream wall atachment is the Coandaboundary layer wall-attachment effect, described quite adequately in theC. L. Mamzic and O. Lew Wood publications listed in the backgroundsection of this specification. Thus, with the control port 56 open andthe control port 62 closed as shown in FIGURE 2, the entire power jetflows in annular form along the inner wall of the tubular casing 12 outthe preferred outlet passage 40 and the preferred outlet port 20.

It should be noted that the control pressure force on the power jetcausing it to diverge, as shown in FIGURE 2, is exerted in an annulararea represented as a section of a cylinder, providing much moreeffective control pressure area than is reasonably possible withconventional planar fluidic devices as disclosed in the prior art.

When the control port 56 is closed and the control port 62 is opened, asillustrated in FIGURE 1, the annular separation bubble 66 is eliminatedthrough replenishment of air entering the control port 62, and at thesame time, the pressure within the power jet is reduced, since theentrained air cannot be replenished through the now closed control port56. The pressure within the jet cannot be fully replenished by reverseflow into the outlet passage 42 because the entrained air flowing alongwith the power jet reduces the flow area, reducing the pressure by theBernoulli effect. Furthermore, a dynamic pressure loss occurs, since airflowing into the outlet passage 42 must reverse its direction whenencountering the entrained air boundary layer. The pressure differentialcauses the power jet to start to converge. This further reduces the flowarea and further increases the pressure differential across the powerjet. The effect is cumulative, so that the power jet completelyconverges in a very short time, a few milliseconds or less if the powerjet is a liquid such as water. If the power jet is gaseous, the time ofconvergence is very much faster. After the jet has converged, the entirepower jet flows into the inner outlet port 44 and out the secondaryoutlet passage 42. This is the condition illustrated in FIGURE 1. Inthis condition the converging jet adheres to itself, and a separationbubble 68 is formed immediately upstream of the point of convergence.This is not the conventional Coanda wall-attachment effect but might bereferred to as a boundary layer self-attachment effect.

As explained, with the parts proportioned generally as shown in FIGURE2, the outlet 20 is the preferred outlet, and the outlet 46 is thesecondary outlet. The power jet will continue to flow out the preferredoutlet 20 even if the control port 56 is subsequently closed, as long asthe control port 62 remains closed. If both control ports are thensimultaneously opened, the power jet will still continue to flow out thepreferred outlet 20, since the diameter of the outlet port 44 is smallerthan the inner diameter of the annular power jet nozzle 32, and thelength of the interaction section 48 is not sufiicient to permit the jetto deteriorate.

On the other hand, if the power jet is flowing out the secondary outlet46 with the control port 56 closed and the control port 62 open, as inFIGURE 1, the power jet will tend to diverge if the control port 56 issubsequently opened, even if the control port 62 remains open, becausethe fluid ejected from the nozzle 32 tends to follow a straight lineunless it is caused to converge or diverge because of a pressurediiferential. Hence, the power jet will switch to the primary outlet 20,although not as fast and without the positive action which occurs if thecontrol port 62 is closed.

Although the outlet port 20 is the preferred outlet in the configurationof FIGURE 2, the flow will continue out the secondary outlet 46 as shownin FIGURE 1 even if the control port 62 is subsequently closed as longas the control port 56 remains closed. This is because sufiicientreplenishment air will flow in the primary outlet 20 so that a pressuredifferential still remains, although reduced, keeping the power jet inconverged form. However, if the control port 56 is then opened, thepower jet flow will almost instantly switch from the secondary outlet 46to the primary outlet 20 because the pressure differential is suddenlyreversed due to replenishment of entrained air within the annular jetthrough the control passage 52; the jet will immediately attach to thewall of the interaction section 48 because of the Coanda effect.

The longitudinal position of the outlet tube 34 may be made adjustableexternally in order to vary the axial length of the interaction section43. This may be accomplished, for example, by providing a suitablethreaded, sealed connection (not shown) between the outlet tube 34 andits juncture with the casing 12 such the outlet tube may be turned in orout to change the axial position of the inner outlet port 44. Suchadjustability may be provided to accommodate power jets of differingviscosity, rates of flow, and pressures. Furthermore, by increasing theaxial length of the interaction section 48 sufiiciently, the outletpassage 42 can be made the preferred outlet and the annular outletpassage 40 the secondary outlet; this results from the inherent tendencyof a free annular jet to converge at a sufficient distance downstream ofthe ejection nozzle. It should be under stood that adjustment of thelength of the interaction chamber may be made while the device is inoperation to accomplish these results.

The embodiment of FIGURE 3 is a monostable fluidic device. This deviceis generally designated by the reference numeral 70 and includes anouter casing 72, a control tube '74, and an outlet tube 76; thesecorrespond to the casing 12, the control tube 22, and the outlet tube34, respectively, of the embodiment of FIGURES l and 2. The deviceincludes an inlet section 78, an interaction section 80, and an outletsection 82. The power jet enters the casing 72 through an inlet port 84and leaves the device through either a primary outlet 86 or a secondaryoutlet 88. The power jet takes an annular form as it passes through anannular passage 90 in the inlet section 78 and is ejected in annularform into the interaction section from an annular power jet nOZZle 92 atthe juncture between the inlet section and the interaction section. Acontrol port 94 is formed at the outward end of the control tube 74 andis adapted to be selectively opened or closed by suitable valve meanssuch as a valve member 96. When the valve member 96 is closed as shownin FIGURE 3, the annular power jet entering the interaction section 80is forced to converge, and a separation bubble 98 is formed immediatelyupstream of the point of convergence. The converging jet thus adheres toitself through the boundary layer self-attachment effect. The convergedjet flows into an inner outlet 100 in the outlet tube 76 and thence outthe secondary outlet 88.

If the control port 94 is opened, the air pressure within the power jetis replenished, and the separation bubble 98 disappears. Since thepressure differential thus disappears, the momentum of the jet causes itto diverge and to fiow into an annular outlet passage 102 and out theprimary outlet 86. A relatively deep step 103 is formed at the junctureof the inlet section 78 and the interaction section 80. The depth of thestep is such that the wall of the interaction chamber is spaced radiallyoutwardly a sutficient amount to prevent the power jet from attaching tothe wall; in other words, there is no Coanda wallattachment in thisembodiment of the invention.

The fluidic device 70 of FIGURE 3 is monostable because the power jetwill always flow out of the preferred outlet 86 unless the control port94 is closed. No additional control port is required for controlling thepath of the power jet. Switching between the preferred outlet 86 and thesecondary outlet 88 and vice versa is accomplished in milliseconds,depending upon the nature of the fluid of the power jet, by opening andclosing the control port 94.

It will be understood that the length of the interaction chamber 80 maybe made adjustable (not illustrated) in the manner indicated inconnection with the embodiment of FIGURES 1 and 2 for the purposesexplained in connection with that embodiment.

A third embodiment of fluidic device according to the present inventionis illustrated in FIGURE 4. This device, which is generally designatedby the reference numeral 110, is a bistable or flip-flop element. Itincludes an outer casing 112, a heavy-walled control tube 114, and anoutlet tube 116. The casing is provided with a power jet inlet port 118and a power jet outlet port 120. Another outlet port 122 is formed atthe outer end of the outlet tube 116. A control port 123 at the outerend of the control tube 114 controls secondary control flow in an axialpassage 124 connected to a radial control passage 125. A second controlport 126 is formed through the wall of the casing 112 immediatelydownstream of a step 127. Flow into the control port 123 is controlledby means of a valve 128, and flow through the control port 126 iscontrolled by means of a valve 130.

The power jet enters the device through the inlet port 118 and isrendered annular in an annular passage 132 between the outer surface ofthe control tube 114 and the inner surface of the casing 112. As in thecase with the previous embodiments, the device comprises an inletsection 134, an interaction section 136, and an outlet section 138. Theaxial length of the interaction chamber 136 may be adjustable (notshown) for the purposes indicated in connection with the embodiments ofFIG- URES l, 2, and 3.

The power jet is ejected into the interaction section 136 through anannular nozzle 140 formed at the juncture of the inlet section and theinteraction section at the step 127. From here the power jet exitsthrough a central outlet passage 142 through the outlet tube 116 and theoutlet port 122, or it is directed into an annular outlet passage 144and is ejected out the outlet When the control port 123 is closed andthe control port 126 is open, as illustrated in FIGURE 4, the power jetconverges and flows out the outlet 122. This results from the Coandaeffect causing formation of an annular separation bubble 146 immediatelydownstream of a step 148 formed in the control tube 114 toward its innerend, radially inwardly from the power jet nozzle 140. Immediatelydownstream of the separation bubble 146 the power jet flow reattaches tothe surface of a nose portion 150 at the inner end of the control tubeand thus flows into an annular opening 152 formed at the end of the nosesection 150 and the entrance to the central outlet passage 142. Fromhere the flow continues to converge, forming a central separation bubble154 immediately upstream of the point of convergence. This secondseparation bubble 154 is formed as a result of the boundary layerself-attachment effect referred to in connection with the first twoembodiments.

If the control port 123 is opened and the control port 126 is closed,the power jet flow switches almost instantly from the outlet 122 to theoutlet 120, as a result of the external Coanda effect and theelimination of the separation bubbles 146 and 154 when the pressure isreplenished through the open control port 123.

The fluidic device 110 is bistable because neither outlet 120 nor outlet122 is preferred. The flow will not switch if the one open control portis subsequently closed as long as the other control port remains closed,regardless of which outlet is being utilized. Hence, the flow willcontinue out the outlet 122 as shown in FIGURE 4 even though the controlport 126 is subsequently closed, as long as the control port 123 remainsclosed. By the same token, the flow will continue out the outlet 120,when it is flowing out that outlet, even though the control port 123 issubsequently closed, as long as the control port 126 remains closed.Thus the flow will continue out one outlet indefinitely until thecontrol port controlling the formation of a separation bubble is openedwhile the other control port is closed. In this case the flow switchesalmost instantaneously, in a matter of milliseconds or less, dependingupon the viscosity and density of the fluid of the power jet. Here againthe formation of and elimination of annular separation bubbles andannular pressure areas on opposite sides of the jet drastically increasethe speed of switching, increase the stability of flow in one state orthe other, and reduce the pressure required for adequate control.

The annular form of the power jet according to the present invention iscompared with the rectangular form of the power jet in a conventionalplanar fluidic device in FIGURES and 6, respectively. Both of thesecross-sectional views are taken at the point of ejection of the powerjet into the interaction section of the respective fluidic elements,with the power jets being of approximately the same cross-sectional areaand with the height of the rectangular jet approximately equal to theoutside diameter of the annular jet. In this comparison the effectivearea subjected to control pressure is over three times as great with theannular power jet of FIGURE 5 as it is with the rectangular power jet ofFIGURE 6. The relative difference varies, of course, with differentconfigurations, but the effective control pressure area for an annularpower jet is always must greater than the control pressure area for aconventional rectangular jet.

A fourth embodiment of fluidic device according tothis invention isillustrated in FIGURE 7 in the form of a fluidic oscillator, generallydesignated by the reference numeral 160. The fluidic oscillator 160includes a casing 162, a heavy-walled control tube 164, and an outlettube 166.

Power jet flow enters through an inlet port 168 and exits through eitheran outlet port 170 or an outlet port 172, the former formed in thecasing 162 and the latter in the outlet tube 166. The device is dividedinto an inlet section 174, an interaction section 176, and an outletsection 178. An annular power jet nozzle 180 is formed at the inner endof the control tube 164 at the juncture between the inlet section andthe interaction section. From the interaction section the flow passesinto an inner outlet port 182 directing flow out the outlet 172, or intoan annular outlet 184 directing flow out the outlet 170.

In this embodiment of the invention the control tube 164 is not providedwith an external control port but instead has an axial control passage186 connected to a closed control loop 188 which terminates with adynamic inlet 190 located in radially spaced relation within the outletport 182, making the outlet port 182 annular as shown.

When the power jet is started, it first flows through the annularpassage 184 out the outlet 170. Entrainment of air within the jetreduces the air pressure and causes it to converge until it enters theannular outlet port 182 and thence out the outlet 172. As it convergesfurther, a portion of the control jet enters the dynamic port 190 andflows into the control loop 188, such that a pressure wave front 192travels in a counter-clockwise direction as shown in FIGURE 7. Thepressure wave front provides pressure of a secondary fluid, in thisinstance partly air and partly water. As this pressure wave frontcompletes the loop through the axial control passage 186 and is ejectedinto the interaction section 176 within the power jet, it temporarilysatisfies a separation bubble 194 which was formed as a result of theboundary layer self-attachment principle. This increases the pressurewithin the ananular power jet so that the jet switches again to theoutlet 170. At this point the cycle starts over again, causing the jetto converge until flow through the control loop causes it to divergeagain. This oscillating action continues as long as the power jet flowcontinues. In this embodiment the control is thus achieved through thecontrol loop 188 and the dynamic inlet 190 instead of through valvemeans as in the previous embodiments.

With a fluidic device 160 as shown in FIGURE 7, the oscillations are inthe nature of 500 cycles per second when the power jet is comprised ofWater. A comparable planar device with a water power jet can achieveonly a fraction of this number of oscillations, in the nature ofapproximately cycles per second. If the power jet is gaseous, theoscillations will be in the order of 40,000 cycles per second ascompared to approximately 10,000 cycles per second as might be expectedwith a comparable planar type fluidic oscillator using the same gaseousmedium for the power jet.

As with the previous embodiments, the operational characteristics of theFIGURE 7 embodiment can be modified by providing suitable means (notshown) for externally changing the length of the internal section 176.In such an adjustable oscillator device the length of the interactionsection 176 is set at an optimum value for a particular usage.Adjustment which shortens the length of the interaction changer, withinlimits, reduces the frequency of oscillations. Lengthening theinteraction section increases the frequency, again within limits. Byproviding adjustability the oscillator device can also be adapted foruse with different fluids.

It should be understood that while the word annular has been used todescribe the form of the power jet in the foregoing description, thisword is used in a broad sense to include not only areas of strictlycircular crosssection but other tube-like shapes, such as those ofgenerally oval or polygonal cross-section. Ordinarily the power jettakes a circular annular cross-sectional shape, but the invention is notso restricted. However, in every instance according to the presentinvention, the power jet is ejected into the interaction chamber intube-like form with all elements of the flow initially parallel to theaxis of symmetry, as distinguished from so-called focused jets of theprior art. It is intended that annular be construed in the senseindicated in both the specification and the claims.

I claim:

1. In a fluidic element, the improvement comprising means for forming atube-like annular power jet of fluid confining a space within said jetfor interaction of said fluid;

oscillatory control means actuated by said power jet for causingalternate convergence and divergence of the power jet,

a central outlet passage which receives the flow of said power jet whenconverged, and

a surrounding annular outlet passage which receives the flow of saidpower jet when diverged.

2. A fluidic element according to claim 1 in which said oscillatorycontrol means comprises a two-ended passage having one end communicatingwith the space within said annular power jet and having its other enddisposed as a dynamic inlet facing downstream in said central outletpassage.

3. In a fluidic element according to claim 1, the improvement comprisingmeans for adjusting the distance between said power jet forming meansand said outlet passages for changing the oscillatory operationalcharacteristics of the fluidic element.

4. In a fluidic element having an inlet for receiving a power jet offluid, the improvement comprising:

means including said power jet fluid for defining an enclosed spacedevoid of physical structure;

first control inlet means opening into said enclosed space for selectiveconvergence of said power jet fluid into a solid stream by boundarylayer selfattachment of said power jet fluid.

5. The combination according to claim 4 in which:

at least a portion of said enclosed space constitutes a hollow fluidinteraction cavity;

and further in which said control inlet communicates with said enclosedspace upstream of the point of convergence of said power jet.

6'. The combination according to claim 5 and further including:

a pluralitj of power fluid outlet ports positioned a predetermineddistance downstream of the point of communication of said control inlet.

7. The'combination according to claim 6 and further including:

fluid forming means for projecting said power jet fluid into saidenclosed space only in a direction parallel to the central axis of saidenclosed space.

8. The combination according to claim 7 and further including:

control means for alternatively closing said first control inlet andcoupling said first control inlet to a secondary fluid source, wherebyclosure of said control inlet causes a low pressure condition withinsaid enclosed space by entrainment of said secondary fluid with saidpower jet fluid for converging said power jet fluid into a solid stream.

9. The combination according to claim 8 and further including:

wall means extending between said inlet and outlet means and spacedtransversely outward of the path of said fluid power jet flow.

10. The combination according to claim 9 and further including:

control means comprising a second control inlet normally communicatingwith a tertiary control fluid source, for controlling selectiveattachment of said power jet fluid with said wall means.

11. The combination according to claim 10 in which:

said power jet fluid normally flows into a predetermined one of saidoutlet ports, absent closure of either of said control inlets;

and further including adjustment means for varying said predetermineddistance between at least one of said outlet ports and said firstcontrol inlet opening to shift said normal power jet fluid flow to adifferent one of said outlet ports.

12. The combination according to claim 11 in which:

said first control inlet communicates with said enclosed space in adownstream direction.

13. A fluid device, for utilizing a power jet of fluid, consistingessentially of:

fluid inlet means; a plurality of fluid outlet ports spaced apredetermined distance from said inlet means; and means including saidpower jet fluid for defining an enclosed space devoid of physicalstructure, intermediate said inlet means and said outlet means, having acentral axis, said means further including a control inlet communicatingwith said enclosed space and alternatively providing and cutting off theflow of a secondary fluid to said enclosed space for selectivelyconverging said power jet fluid from opposite sides of said central axisinto a solid stream by a boundary layer self-attachment effect. 14. Afluidic device having an inlet, an interaction and an outlet zone,comprising:

inlet means within said inlet zone for developing an annular power jetand for projecting said annular power jet into said interaction zone,said annular power jet defining, within said interaction zone, aconfined space devoid of physical structure; first control meansincluding a control fluid conduit opening into said confined space fornormally providing control fluid flow thereto to replace that entrainedby said annular power jet but adapted for restricting control fluid flowto said confined space to selectively converge said annular power jetinto a single stream by boundary layer self-attachment of the fluid ofsaid annular power jet; and outlet means within said outlet zonecomprising a plurality of separate outlet channels for collecting saidpower jet fluid flowing from said interaction zone. 15. In a fluidicelement according to claim 14, the improvement comprising means foradjusting the distance between said power jet forming means and saidoutlet passages for changing the operational characteristics of thefluidic element. 16. In a fluidic element according to claim 14, theimprovement comprising second control means for selectively applying andcutting ofl pressure of said secondary fluid to an external annular areaof said power jet downstream of said inlet means; whereby said power jetconverges when said second control means supplies pressure of saidsecondary fluid while said first control means cuts off pressure of saidsecondary fluid, and whereby said power jet diverges when said firstcontrol means supplies pressure of said secondary fluid while saidsecond control means cuts off pressure of said secondary fluid. 17. In afluidic element according to claim 14, the improvement comprising acentral outlet passage which receives the entire flow of said power jetwhen said second control means supplies pressure of said secondary fluidwhile said first control means cuts oif pressure of said secondaryfluid, and surrounding annular outlet passage which receives the entireflow of said power jet when said first control means applies pressure ofsaid secondary fluid while said second control means cuts off pressureof said secondary fluid. 18. A fluidic device having an inlet, aninteraction and an outlet zone, comprising:

inlet means within said inlet zone adapted for developing power jetfluid flow of predetermined crosssectional configuration with portionsof said power jet fluid lying on opposite sides of a predetermined axisof said inlet means and for projecting said power jet fluid into saidinteraction zone with said predetermined cross-sectional configuration;

means within said interaction zone and including said power jet fluidfor defining a confined space devoid of physical structure; controlmeans including a control fluid inlet opening into said confined spacefor normally providing control fluid flow thereto to replace thatentrained by said power jet fluid but adapted for restricting controlfluid flow to said confined space to selectively converge said power jetfluid into a single stream by boundary layer self-attachment of saidpower jet fluid; an outlet means within said outlet zone comprising alurality of separate outlet channels for collecting said power jet fluidflowing from said interaction zone. 19. The fluidic device of claim 18and further including means for adjusting the distance between saidinlet means and said outlet means for varying the operationalcharacteristics of said fluidic device.

References Cited UNITED STATES PATENTS Carlson l3781.5 Bliss et al13781.5 XR

Palmisano 1378l.5

Jones 137-815 XR Boothe l3781.5 Lewis et al. 137-81.5 XR Bjornsen et a113781.5 Swartz 13781.5

SAMUEL SCOTT, Primary Examiner

